Integrated lead or wireless disk drive head suspensions are well known and commercially available. These devices generally include a load beam (typically formed from spring material such as stainless steel), a flexure (also typically formed from stainless steel) on a distal end of the load beam, conductors (also known as traces or leads and typically formed from copper or copper alloys) extending toward the proximal end of the load beam from the flexure, and a dielectric insulator between the conductors and adjacent stainless steel portions. Suspensions of these types can be formed from a laminate including layers of stainless steel and copper separated by a layer of dielectric. In one approach (e.g., Bennin et al. U.S. Pat. No. 5,864,445), the load beam and flexure are etched and formed from the same stainless steel layer of the laminate, and the conductors are etched from the conductor layer. Another approach (e.g., Supramaniam et al. U.S. Pat. No. 6,014,290) includes a so-called integrated lead flexure that is formed from the laminate material and a load beam that is formed separately from stainless steel. The integrated lead flexure is welded or otherwise attached to the load beam.
The leads, in connection with the underlying stainless steel (a conductor layer that functions as a ground plane) form a transmission line for coupling electronic read/write signals to and from a magnetic head mounted to the flexure. Windows or apertures are sometimes formed in the stainless steel below the ground plane to reduce the impedance of the transmission line. These windows are typically about 1 mm in length (i.e., in the longitudinal direction of the leads). Unfortunately, these transmission line structures are still susceptible to eddy current losses.
There remains, therefore, a continuing need for improved transmission line structures for integrated lead suspensions. In particular, there is a need for relatively low loss transmission line structures that are capable of being manufactured with a range of impedances. To be commercially viable the structures should be capable of being efficiently manufactured.